1. Field of the Invention
The present invention relates generally to electronic device authentication.
2. Description of the Related Art
In the Bluetooth Specification, “Specification of the Bluetooth System—Core”, v.1.0A, Jul. 26th 1999, pp. 18–19, 95, 149–154, 169–170, 194–200, 226, 319, 537, 1029, and 1031, the so-called Bluetooth short range radio link between Bluetooth enabled devices is described, particularly, the Bluetooth frequency bands, the concept of master and slave devices, and security using authentication of devices. Bluetooth (BT) is a specification for small form factor, low-cost, short-range radio links between mobile PCs, mobile phones, and other such devices. Bluetooth radio arose out of an initiative among leaders in the telecommunication and computer industries to make a global standard for wireless connectivity. The standard relies on a low power radio link operating at 2.4 Gigahertz. Bluetooth-provisioned devices normally must be physically close to each other (i.e., within 100 meters) to communicate. Bluetooth includes a robust authentication mechanism that ensures that a Bluetooth device only communicates with other devices for which it is authenticated, and not with any random device that comes into its range. Bluetooth radio uses a fast acknowledgement and frequency hopping scheme to make the link robust. Devices avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet. Compared with other systems operating in the same frequency band, the Bluetooth radio typically hops faster and uses shorter packets. This makes Bluetooth radio more robust than other systems.
The Bluetooth authentication scheme works generally as follows. A user enters a numerical code (a personal identification number or PIN) in the two devices to establish a Bluetooth link for the first time. The PIN can be any number, but it must be the same on both devices. Once this is done, the devices communicate with each other using Bluetooth transceivers to verify that the PIN numbers match. If so, one device generates unique key information based on a device address, which is unique for each device. This unique key (generated by one of the devices) is stored in both devices and used to authenticate the two devices for any subsequent Bluetooth link between them. In particular, the key exchanged upon link initialization identifies a unique link and can be used reliably for subsequent authentication when the link is re-established.
The feature that ensures security in a Bluetooth system is the need for physical proximity to establish a link, i.e., the user must enter the numerical code on both devices when the devices are in close proximity. If the devices are more than 100 meters apart, the initial Bluetooth link cannot be established.
Wide area networks also use basic authentication to enable electronic devices to communicate with each other. The most common and popular wide area network is the Internet. Internet service providers typically restrict access on their servers to given users. Normally, this is achieved by requiring a prospective user (e.g., a user of a client machine running a web browser) to enter a userid and password combination.